Electronics Engineering - Online Test
Q1. The doping concentrations on the p-side and n-side of a silicon diode are 1 × 1016 cm-3 and 1 × 1017 cm-3, respectively. A forward bias of 0 3. V is
applied to the diode. At T = 300 K, the intrinsic carrier concentration of silicon ni = 1.5 × 1010 cm-3 and (kT/q) = 26 mV. The electron concentration at the edge of
the depletion region on the p-side is
Answer : Option A
Explaination / Solution:
Given the doping concentration on p-side
NA = 1 × 1016 cm-3
V = 0.3 V
Intrinsic carrier concentration,
So, the equilibrium electron concentration on the p-side is
Therefore, the electron at the edge of the depletion region on the p-side is obtained
as
Q2. The two numbers represented in signed 2’s complement form are P + 11101101 and Q = 11100110. If Q is subtracted from P, the value obtained in signed 2’s complement is
Answer : Option B
Explaination / Solution:
Q3. The two-port network P shown in the figure has ports 1 and 2, denoted by terminals (a, b) and
(c, d), respectively. It has an impedance matrix Z with parameters denoted by zij. A 1Ω resistor
is connected in series with the network at port 1 as shown in the figure. The impedance matrix
of the modified two-port network (shown as a dashed box) is
Answer : Option C
Explaination / Solution:
No Explaination.
Q4. 
The asymptotic approximation of the log-magnitude vs frequency plot of a system containing only real poles and zeros is shown. Its transfer function is
Answer : Option B
Explaination / Solution:
Q5. In a digital communication system, the overall pulse shape p(t) at the receiver before the sampler has the Fourier transform P(f). If the symbols are transmitted at the rate of 2000 symbols per second, for which of the following cases is inter symbol interference zero?
Answer : Option B
Explaination / Solution:
For ISI free pulse,
If P(t) is having spectrum P(f)
Then 
= constant
= constantRs = 2KSpa
Thin condition is met by pulse given in option B.
Q6. If the Laplace transform of a signal 
then its final value is
then its final value is
Answer : Option D
Explaination / Solution:
Final value theorem is applicable only when all poles of system lies in left half of S -plane. Here s = 1 is right s −plane pole. Thus it is unbounded.
Q7. The peak electric field in the device is
Answer : Option B
Explaination / Solution:
The peak electric field in device is directed from p to n and is 
Q8. Which of the following Boolean Expressions correctly represents the relation
between P,Q,R and M1
Answer : Option D
Explaination / Solution:
Q9. The L-C circuit shown in the figure has an inductance L = 1mH and a capacitance
C = 10µF. 
The initial current through the inductor is zero, while the initial capacitor voltage is 100 V. The switch is closed at t = 0. The current i through the circuit is:
Answer : Option D
Explaination / Solution:
No Explaination.
Q10. The unit-step response of a unity feedback system with open loop transfer function G(s) 
is shown in the figure. The value of K is
is shown in the figure. The value of K is
Answer : Option D
Explaination / Solution:
No Explaination.
